10: Fort Yarrok

Campaign

Waves: 5

Starting Energy: 1600

Lives: 20

There are two blocked tower slots in the map, three spawn points and two checkpoints. Most of the enemy traffic will take place in the western side of the map since that's where two of the spawn points merge. Place two infantry towers in the slots near the exits and upgrade them to LV2 both. Now occupy the other slots, preferably place a rocket or laser tower in the lone slot in the third, short path to the west. By the third wave, enemy fliers will start swarming in with tons of ground troops so make sure you focus fire on them to prevent them from escaping your defenses. Save your Tesla Tower charges as much as possible.

After clearing the fifth wave, Haxor will deploy the Tyrannus. At this point, your infantry and most of the towers should be at least LV3. Focus fire on the Tyrannus, and move your hero and change the waypoint of your units as necessary to avoid the explosive salvo it will regularly release. If you still have some Tesla charges and of course, airstrikes, don't hesitate to use it against this boss since the longer the battle drags on, the harder you'll get hit by its missile rain.

Completing this mission will unlock Challenges 20-25

Veteran

Waves: 6

Starting Energy: 1200

Lives: 1

In this mode, you can only use Rocket Towers and Laser towers. You may need to call in reinforcements as soon as the battle starts to guard the two checkpoints. There's the same number of tower slots and two blocked ones. Enemies will also use the teleporters on the side of the two roads to get past your blockade and catch you off guard. Position your reinforcement soldiers near this portal to guard it from any enemy that will try to sneak in. Just upgrade once you have enough cash then use the Tesla Coil as your in case of an immergency.

Spec Ops

Waves: 1

Starting Energy: 1500

Lives: 1

Apply the same initial setup as you did in the campaign mode. Uprade your infantry towers as soon as possible so they can resist the fire damage from the rocketeers' blast. Early in the wave, you'll also have to deal with two destroyers so make sure to focus fire on them or use your Airstrike (save your Tesla Tower for emergencies requiring faster response) A large wave of Crusaders and Rocketeers will also follow so have your Tesla Tower ready. Keep upgrading your towers; all of them should be at least LV2 in the later part of the wave.